Adding an easy way to allow inline style attributes through sanitization

tests/html/node_validator_test.dart

Index: tests/html/node_validator_test.dart
diff --git a/tests/html/node_validator_test.dart b/tests/html/node_validator_test.dart
index 7f76762f6ac3e69564e036ac30b292c7dce8ee0e..ae25743266714b8c777efc47c55f5151201ddbea 100644
--- a/tests/html/node_validator_test.dart
+++ b/tests/html/node_validator_test.dart
@@ -87,6 +87,11 @@ main() {
         '<div><script></script><script></script></div>',
         '<div></div>');
 
+    testHtml('blocks inline styles',
+        validator,
+        '<div style="background: red"></div>',
+        '<div></div>');
+
     testHtml('blocks namespaced attributes',
         validator,
         '<div ns:foo="foo"></div>',
@@ -373,6 +378,34 @@ main() {
           '<foreignobject width="100" height="150"></foreignobject>'
         '</svg>');
     });
+
+    group('allowInlineStyles', () {
+      var validator = new NodeValidatorBuilder()
+          ..allowTextElements()
+          ..allowInlineStyles();
+
+      testHtml('allows inline styles',
+          validator,
+          '<span style="background-color:red">text</span>');
+
+      testHtml('blocks other attributes',
+          validator,
+          '<span class="red-span"></span>',
+          '<span></span>');
+
+      validator = new NodeValidatorBuilder()
+          ..allowTextElements()
+          ..allowInlineStyles(tagName: 'span');
+
+      testHtml('scoped allows inline styles on spans',
+          validator,
+          '<span style="background-color:red">text</span>');
+
+      testHtml('scoped blocks inline styles on LIs',
+          validator,
+          '<li style="background-color:red">text</li>',
+          '<li>text</li>');
+    });
   });
 
   group('throws', () {